Figure 4. Excess ¹²C-equivalent (mg) of needles and roots for (a) interior Douglas-fir donors and (b) ponderosa pine receivers 6 days following ¹³C-CO₂ labelling on donors exposed to insect and manual defoliation, and (c) its partition in needles and roots.

Pathway means with different letters differed significantly within their respective defoliation treatments at α = 0.05.